You can hardly be an architectural illustrator, working in the industry today, without having to work with a Revit Architectural model. This is how I feel about the workflow...
In the mid 80's, I started creating architectural renderings for a living. By getting paid for my work, I guess you can say; I was a professional illustrator.
My architectural renderings were invariably done with black pen, on cold press paper. I spent a lot of time working through perspective, light, and shadow. Not until I got everything worked out on paper, with a blue pencil, did I commence drawing.
Preparing a perspective architectural rendering is a science... If anything is off perspective, your rendering will look wrong. It's amazing and has been a personal interest of the mind, how people perceive things. Our minds eye expects to see something, and if that something isn't what it expected to see, red flags are raised. If a person, in your architectural rendering is off scale, it will ruin your viewers experience. So, I can comfortably say, preparing a drawing was 1/2 the work.
Unless an architectural rendering you were working on is a personal project, your time is a premium, and time is money. When I got my first PC, I discovered a shortcut. With my PC, I was able to mass out primitives, work out perspective, and study light and shadow. What took many hours, on paper with pen, would only take minutes with the PC. Now, with the perspective worked out, I could spend more time on the creative part of my architectural renderings.
Fast forward couple decades, to the present time, and I see the same thing happening. Once the PC could handle more than primitives, I started rendering 100% digitally. I put down the pen and paper, picked up the mouse, and everything is now digital. So, instead of spending a lot of time working out perspective on paper, I found myself spending a lot if time trying to model from 2D architectural drawings. To get a good render digitally, you have to build a clean model. The process from 2D wasn't pretty. It served a purpose; I found all the construction errors on the drawing but at my expense. I was commissioned to illustrate, not to do a construct-ability study.
Over the past several years, I have been asked to take over a lot of Revit Architectural models. Although these models are not modeled nearly clean enough for a high quality render, I wasn't stuck with drawings that didn't work. Although I end up remodeling most of the models I get, there is still savings. Everything has been worked out, so I can spend a lot less time modeling through all the issues, and I can spend more time on the creative part, which is why I do what I do.